Meeting Abstract
There is extensive literature on intraspecific variability of thermoregulation due to habitat, temperature availability, and seasonality, but fewer studies focus on variability due to sex. Sex-specific thermoregulatory strategies may affect relative fitness disproportionately, driving different responses to environmental changes (e.g., climate change). The common chuckwalla (Sauromalus ater) is a great model for investigating sex differences in thermoregulation because it is sexually dimorphic in behavior; males hold territories that they actively patrol and defend. We hypothesized that male and female chuckwallas thermoregulate to the same temperatures and to the same extent, but that males spend more time thermoregulating outside of refuges (e.g. to defend territories) compared to non-territorial females. Body temperatures of free-ranging adult chuckwallas were continuously recorded from May to early July 2016, as were operative temperatures in crevices and above-ground basking sites that provide context for lizard body temperatures. We compared the effects of month and sex on the average time chuckwallas selected body temperatures above, below, and within their preferred temperature range (34-39 °C) for May-July. Chuckwallas on average spent more time below 34 °C in May, and above 39 °C in July. This reflects temporal and spatial changes in available suitable operative temperatures. On average, females in June spent significantly more time at body temperatures below preferred range compared to males. This may reflect different late–season reproductive priorities, with males seeking final mating opportunities aboveground, and females seeking underground nesting sites.
